Novel human Jak2 kinase

ABSTRACT

The present invention provides a polynucleotide (hjak2) which identifies and encodes a novel human Jak2 kinase (HJAK2) which was expressed in the placenta. The present invention also provides for antisense molecules and oligomers designed from the nucleotide sequence or its antisense. The invention further provides genetically engineered expression vectors and host cells for the production of purified HJAK2 peptide, antibodies capable of binding to HJAK2, inhibitors which bind to HJAK2 and pharmaceutical compositions based on HJAK2 specific antibodies or inhibitors. The invention specifically provides for diagnostic assays based on altered hjak2 expression and which allow identification of such a condition. These assays utilize probes which comprise oligomers, fragments, or portions of hjak2 or its regulatory elements or antibodies specifically binding HJAK2.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a divisional of U.S. application Ser. No. 09/467,100, filed on Dec. 10, 1999, which is a divisional of U.S. application Ser. No. 09/196,480, filed on Nov. 19, 1998, now U.S. Pat. No. 6,019,966, which is a divisional of U.S. application Ser. No. 08/567,508, filed on Dec. 5, 1995, now U.S. Pat. No. 5,914,393, all of which are incorporated herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to a novel, human Jak2 kinase isolated from human placenta and to the use of this novel protein and its nucleic acid sequence in the diagnosis, study, prevention, and treatment of disease.

BACKGROUND OF THE INVENTION

JAK kinases are Janus family nonreceptor protein-tyrosine kinases (NR-PTK) that lack transmembrane regions and form functional complexes with the intercellular regions of other cell surface receptors. They were first identified as the products of mutant oncogenes in cancer cells where their activation was no longer subject to normal cellular controls. Described JAK kinases include Jak1, Jak2, and Jak3, which all share the conserved kinase domain. In addition, these proteins have 5 to 100 amino acid residues located on either side of, or inserted into loops of, the carboxyterminal kinase domain which allow the regulation of each kinase as it recognizes and interacts with its target protein. Known target proteins include growth hormone receptor, prolactin receptor, erythropoietin receptor, cytokine receptors and others which utilize the common chain known as gp130. These receptors are unique both in their ability to recruit multiple PTKs and in the diversity of their responses within different cell types (Taniguchi T (1995) Science 268:251-55). Genetic evidence places these kinases in the interferon α and γ signal transduction pathways which are widely expressed in mammalian cells.

Kinases regulate many different cell proliferation, differentiation, and signaling processes by adding phosphate groups to proteins. The high energy phosphate which drives activation is generally transferred from adenosine triphosphate molecules (ATP) to a particular protein by the PTKs, and the transfer process is roughly analogous to turning on a molecular switch. When the switch goes on, the kinase activates a metabolic enzyme, regulatory protein, receptor, cytoskeletal protein, ion channel or pump, transcription factor, or another kinase. For example, in their normal role, the JAK NR-PTKs are capable of regulating tyrosine phosphorylation of STAT proteins, signal transducers and activators of transcription, such that they translocate to the nucleus and bind DNA (David M et al. (1995) Science 269:1721-1723). In contrast, uncontrolled kinase signaling has been implicated in inflammation, oncogenesis, arteriosclerosis, and psoriasis.

Almost all kinases contain a similar 250-300 amino acid catalytic domain. The N-terminal domain generally folds into a two-lobed structure to bind and orient ATP (or GTP) donor molecules. The larger C terminal lobe binds the protein substrate and carries out the transfer of phosphate from ATP to the hydroxyl group of a tyrosine residue. The primary structure of the kinase domain is conserved in the residues: G₅₀ and G₅₂ in subdomain I, K₇₂ in subdomain II, G₉₁ in subdomain III, E₂₀₈ in subdomain VIII, D₂₂₀ and G₂₂₅ in subdomain IX, and the amino acid motifs of subdomains VIB, VIII and IX (Hardie G and Hanks S (1995) Academic Press, San Diego Calif.).

The novel human Jak2 kinase, hjak2, of the present application shows significant conservation of the diagnostic kinase residues which allowed its identification from among the isolated cDNAs of a placenta library, the anatomy and physiology of which is briefly described below.

The placenta is a thickened disk-shaped temporary organ that interchanges gases, nutrients, hormones, excretory products, humoral antibodies (IgG), and any other circulating substances between the maternal and fetal bloodstreams. Receptors facilitate the transport of glucose, amino acids, and IgG directly from maternal blood to fetal blood. The placenta is the only organ composed of cells derived from two individuals, the fetal extraembryonic chorion and the maternal endometrium. The boundary between these two tissues is marked by extracellular products of necrosis referred to as fibrinoid. This boundary results from the various tissue interactions, immunological responses, etc. which occur in the placenta.

The major tissue interaction involves the expression of paternal antigens by the chorionic villi which is directly adjacent to maternal blood. Although the mother initiates an immunological response, fetal tissue is not typically rejected. This is attributed to the fact that the fetus only expresses major histocompatibility complex (MHC) I, and not MHC II which is the major cause of organ allograft rejection. In addition, uterine secretions during early gestation contain significant amounts of glucose and glycoproteins which may participate in local immunosuppression.

Although infections by bacteria, viruses, mycoplasmas, or parasites may ascend from the endocervical canal or reach the placenta through maternal blood, they rarely cause gross pathological changes because of maternal immune defense.

Soon after implantation, fetal villi begin to control maternal physiology to create an optimal environment for development. This involves the production of chorionic gonadotropin, estrogen and progesterone, chorionic somatomammotropin, insulin-like growth factors, platelet derived growth factor, prolactin, and various cytokines. These and other factors such as hjak2 certainly regulate the numerous activities (respiratory, immunological, gastrointestinal, and urinary) which occur within the placenta and between maternal and fetal tissues.

The anatomy and physiology of human placenta is reviewed, inter alia, in Benirschke and Kaufmann, (1992) Pathology of the Human Placenta, Springer-Verlag, New York N.Y., pp. 542-635; Herrera Gonzalez and Dresser (1993) Dev Comp Immunol 17(1):1-18; Mitchell et al. (1993) Placenta 14:249-275; Naeye (1992) Disorders of the Placenta, Fetus, and Neonate: Diagnosis and Clinical Significance, Moseby Year Book, St. Louis Mo.; and Rutanen (1993) Ann Med 25:343-347.

SUMMARY

The present invention relates to a novel human Jak2 kinase and to the use of the protein and its nucleic acid sequence in the study, diagnosis, prevention, and treatment of diseases. Human Jak2 kinase (hjak2) was first identified as a partial nucleotide sequence in Incyte Clone 179527 during a computer search for nucleotide sequence alignments among the cDNAs of a placenta library. A modified XL-PCR procedure, specially designed oligonucleotides, and cDNAs of the placenta library were used to extend Incyte Clone 179527 to full length. The assembled nucleotide sequence (SEQ ID NO: 1), hjak2, encodes the polypeptide HJAK2 (SEQ ID NO: 2). Computer search and alignment of the full length amino acid sequence showed that HJAK2 has 92% similarity to murine Jak2 kinase (MUSPTK1; GenBank GI 409584; Wilks A F (1989) Proc Nat Acad Sci 86:1603-7), which in turn has 96% sequence similarity with human Jak1 kinase. These homologies and the conserved residues, G₄₈, K₇₃, E₁₉₂, and D₂₂₀ which all lie within the catalytic domain contributed to the naming and uses of hjak2.

The complete nucleic acid sequence encoding hjak2, SEQ ID NO: 1 disclosed herein, provides the basis for the design of antisense molecules useful in diminishing or eliminating expression of the genomic nucleotide sequence. For example, hjak2 or its oligonucleotides, fragments, portions, or complement, may be used in diagnostic hybridization or amplification assays of biopsied tissue to detect and/or quantify abnormalities in gene expression associated with an immunological disorder. The present invention also relates, in part, to the inclusion of the nucleic acid sequence in an expression vector which can be used to transform host cells or organisms. Such transgenic hosts are useful for production and recovery of the encoded HJAK2.

The invention further comprises using purified HJAK2 polypeptide to produce antibodies or to identify antagonists or inhibitors which bind HJAK2. Anti-HJAK antibodies may be used in membrane, tissue-based or ELISA technologies to detect any disease state or condition related to the aberrant expression of HJAK2. Antibodies, antagonists or inhibitors can be used to bind HJAK2 preventing the transfer of high energy phosphate molecules and therefore signal transduction. The invention also comprises pharmaceutical compositions containing the peptide, antibodies, antagonists or inhibitors for the diagnosis, prevention or treatment of conditions associated with altered or uncontrolled hjak2 expression. These conditions may include, but are not limited to: arteriosclerosis, asthma, bronchitis, emphysema, inflammatory bowel disease, leukemia, oncogenesis, osteoarthritis, psoriasis, rheumatoid arthritis, septic shock, and systemic lupus erythematosus. Steps for testing a biological sample with probes, oligomers, fragments or portions of the hjak2 nucleotide sequence or antibodies produced against the purified HJAK2 protein are provided.

Antisense molecules, antibodies, antagonists or inhibitors (including proteins, peptides, oligopeptides or organic molecules capable of compromising or modulating HJAK2 expression) may also be used for therapeutic purposes, for example, in neutralizing the abberrent activity of a HJAK2 associated with, for example, inflammation or oncogenesis. The present invention also provides for pharmaceutical compositions for the treatment of disease states associated with aberrant expression of hjak2 comprising the forementioned antisense molecules, antibodies, antagonists or inhibitors.

DESCRIPTION OF THE FIGURES

FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G, and 1H display an alignment of the nucleic acid (SEQ ID NO: 1) and amino acid (SEQ ID NO: 2) sequences of human jak2 kinase. Alignments shown in these and in the following figures were produced using the multisequence alignment program of DNASTAR software (DNASTAR Inc., Madison Wis.).

FIGS. 2A, 2B, 2C, 2D, and 2E show the amino acid sequence similarity between HJAK2 (SEQ ID NO: 2) and MUSPTK1 (GI 409584; SEQ ID NO: 3) and.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

As used herein, the abbreviation for the novel human Jak2 kinase in lower case (hjak2) refers to a gene, cDNA, RNA, or nucleic acid sequence, while the upper case version (HJAK2) refers to a protein, polypeptide, peptide, oligopeptide, or amino acid sequence.

An “oligonucleotide” or “oligomer” is a stretch of nucleotide residues which has a sufficient number of bases to be used in a polymerase chain reaction (PCR). These short sequences are based on (or designed from) genomic or cDNA sequences and are used to amplify, confirm, or reveal the presence of an identical, similar or complementary DNA or RNA in a particular cell or tissue. Oligonucleotides or oligomers comprise portions of a DNA sequence having at least about 10 nucleotides and as many as about 50 nucleotides, preferably about 15 to 30 nucleotides. They are chemically synthesized and may be used as probes.

“Probes” are nucleic acid sequences of variable length, preferably between at least about 10 and as many as about 6,000 nucleotides. They are used in the detection of identical, similar, or complementary nucleic acid sequences. Longer length probes are usually obtained from a natural or recombinant source, are highly specific and much slower to hybridize than oligonucleotides. They may be single- or double-stranded and are carefully designed to have specificity in PCR, hybridization membrane-based, or ELISA-like technologies.

“Reporter” molecules are chemical moieties used for labelling a nucleic or amino acid sequence. They include, but are not limited to, radionuclides, enzymes, fluorescent, chemiluminescent, or chromogenic agents. Reporter molecules associate with, establish the presence of, and may allow quantification of a particular nucleic or amino acid sequence.

A “portion” or “fragment” of a polynucleotide or nucleic acid comprises all or any part of the nucleotide sequence having fewer nucleotides than about 6 kb, preferably fewer than about 1 kb which can be used as a probe. Such probes may be labelled with reporter molecules using nick translation, Klenow fill-in reaction, PCR or other methods well known in the art. After pretesting to optimize reaction conditions and to eliminate false positives, nucleic acid probes may be used in Southern, northern or in situ hybridizations to determine whether DNA or RNA encoding the protein is present in a biological sample, cell type, tissue, organ or organism.

“Recombinant nucleotide variants” are polynucleotides which encode a protein. They may be synthesized by making use of the “redundancy” in the genetic code. Various codon substitutions, such as the silent changes which produce specific restriction sites or codon usage-specific mutations, may be introduced to optimize cloning into a plasmid or viral vector or expression in a particular prokaryotic or eukaryotic host system, respectively.

“Linkers” are synthesized palindromic nucleotide sequences which create internal restriction endonuclease sites for ease of cloning the material of choice into various vectors. “Polylinkers” are engineered to include multiple restriction enzyme sites and provide for the use of both those enzymes which leave 5′ and 3′ overhangs such as BamHI, EcoRI, PstI, KpnI and Hind III or which provide a blunt end such as EcoRV, SnaBI and StuI.

“Control elements” or “regulatory sequences” are those nontranslated regions of the gene or DNA such as enhancers, promoters, introns and 3′ untranslated regions which interact with cellular proteins to carry out replication, transcription, and translation. They may occur as boundary sequences or even split the gene. They function at the molecular level and along with regulatory genes are very important in development, growth, differentiation and aging processes.

“Chimeric” molecules are polynucleotides or polypeptides which are created by combining one or more of nucleotide sequences of this invention (or their parts) with additional nucleic acid sequence(s). Such combined sequences may be introduced into an appropriate vector and expressed to give rise to a chimeric polypeptide which may be expected to be different from the native molecule in one or more of the following characteristics: cellular location, distribution, ligand-binding affinities, interchain affinities, degradation/turnover rate, signalling, etc.

“Active” refers to those forms, fragments, or domains of an amino acid sequence which display the biologic and/or immunogenic activity characteristic of the naturally occurring peptide.

“Naturally occurring HJAK2” refers to a polypeptide produced by cells which have not been genetically engineered or which have been genetically engineered to produce the same sequence as that naturally produced. Specifically contemplated are various polypeptides which arise from post-transnational modifications. Such modifications of the polypeptide include but are not limited to acetylation, carboxylation, glycosylation, phosphorylation, lipidation and acylation.

“Derivative” refers to those polypeptides which have been chemically modified by such techniques as ubiquitination, labelling (see above), pegylation (derivatization with polyethylene glycol), and chemical insertion or substitution of amino acids such as ornithine which do not normally occur in human proteins.

“Recombinant polypeptide variant” refers to any polypeptide which differs from naturally occurring HJAK2 by amino acid insertions, deletions and/or substitutions, created using recombinant DNA techniques. Guidance in determining which amino acid residues may be replaced, added or deleted without abolishing characteristics of interest may be found by comparing the sequence of HJAK2 with that of related polypeptides and minimizing the number of amino acid sequence changes made in highly conserved regions.

Amino acid “substitutions” are defined as one for one amino acid replacements. They are conservative in nature when the substituted amino acid has similar structural and/or chemical properties. Examples of conservative replacements are substitution of a leucine with an isoleucine or valine, an aspartate with a glutamate, or a threonine with a serine.

Amino acid “insertions” or “deletions” are changes to or within an amino acid sequence. They typically fall in the range of about 1 to 5 amino acids. The variation allowed in a particular amino acid sequence may be experimentally determined by producing the peptide synthetically or by systematically making insertions, deletions, or substitutions of nucleotides in the hjak2 sequence using recombinant DNA techniques.

A “signal or leader sequence” is a short amino acid sequence which or can be used, when desired, to direct the polypeptide through a membrane of a cell. Such a sequence may be naturally present on the polypeptides of the present invention or provided from heterologous sources by recombinant DNA techniques.

An “oligopeptide’ is a short stretch of amino acid residues and may be expressed from an oligonucleotide. It may be functionally equivalent to and either the same length as or considerably shorter than a “fragment”, “portion”, or “segment” of a polypeptide. Such sequences comprise a stretch of amino acid residues of at least about 5 amino acids and often about 17 or more amino acids, typically at least about 9 to 13 amino acids, and of sufficient length to display biologic and/or immunogenic activity.

An “inhibitor” is a substance which retards or prevents a chemical or physiological reaction or response. Common inhibitors include but are not limited to antisense molecules, antibodies, antagonists and their derivatives.

A “standard” is a quantitative or qualitative measurement use for comparison. Preferably, it is based on a statistically appropriate number of samples and is created to use as a basis of comparison when performing diagnostic assays, running clinical trials, or following patient treatment profiles. The samples of a particular standard may be normal or similarly abnormal.

“Animal” as used herein may be defined to include human, domestic (cats, dogs, etc), agricultural (cows, horses, sheep, goats, chicken, fish, etc) or test species (frogs, mice, rats, rabbits, simians, etc.).

“Conditions” includes cancers, disorders or diseases in which hjak2 activity may be implicated. These specifically include, but are not limited to, anemia, arteriosclerosis, asthma, bronchitis, emphysema, gingivitis, inflammatory bowel disease, insulin-dependent diabetes mellitus leukemia, multiple endocrine neoplasias, osteoarthritis, osteoporosis, pulmonary fibrosis, rheumatoid arthritis, septic shock syndromes, and systemic lupus erythematosus.

Since the list of technical and scientific terms cannot be all encompassing, any undefined terms shall be construed to have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. Furthermore, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. For example, reference to a “restriction enzyme’ or a “high fidelity enzyme” may include mixtures of such enzymes and any other enzymes fitting the stated criteria, or reference to the method includes reference to one or more methods for obtaining cDNA sequences which will be known to those skilled in the art or will become known to them upon reading this specification.

Before the present sequences, variants, formulations and methods for making and using the invention are described, it is to be understood that the invention is not to be limited only to the particular sequences, variants, formulations or methods described. The sequences, variants, formulations and methodologies may vary, and the terminology used herein is for the purpose of describing particular embodiments. The terminology and definitions are not intended to be limiting since the scope of protection will ultimately depend upon the claims.

Description of the Invention

The present invention provides for a purified polynucleotide which encodes a novel human Jak2 kinase which is expressed in human cells or tissues. The human Jak2 kinase (hjak2; Incyte Clone 179527) was first identified among the cDNAs from a placenta cDNA library. The naming and proscribed uses of the present invention are based in part on the conserved residues-found in HJAK2. These particularly include the residues G48, K₇₃, E₁₉₂, and D₂₂₀, which are all found within the catalytic domain. Computer search and alignment of the full length amino acid sequences showed that HJAK2 has 92% similarity to murine Jak2 kinase (MUSPTK1; GenBank GI 409584; Wilks A F (1989) Proc Nat Acad Sci 86:1603-7), which in turn has 96% sequence similarity with human Jak1 kinase.

Purified nucleotide sequences, such as hjak2, have numerous applications in techniques known to those skilled in the art of molecular biology. These techniques include their use as PCR or hybridization probes, for chromosome and gene mapping, in the production of sense or antisense nucleic acids, in screening for new therapeutic molecules, etc. These examples are well known and are not intended to be limiting. Furthermore, the nucleotide sequences disclosed herein may be used in molecular biology techniques that have not yet been developed, provided the new techniques rely on properties of nucleotide sequences that are currently known, including, but not limited to, such properties as the triplet genetic code and specific base pair interactions.

As a result of the degeneracy of the genetic code, a multitude of HJAK2-encoding nucleotide sequences may be produced. Some of these will bear only minimal homology to the endogenous sequence of any known and naturally occurring Jak2 kinase sequence. This invention has specifically contemplated each and every possible variation of nucleotide sequence that could be made by selecting combinations based on possible codon choices. These combinations are made in accordance with the standard triplet genetic code as applied to the nucleotide sequence of naturally occurring HJAK2 and all such variations are to be considered as being specifically disclosed.

Although the hjak2 nucleotide sequence and its derivatives or variants are preferably capable of identifying the nucleotide sequence of the naturally occurring HJAK2 under optimized conditions, it may be advantageous to produce HJAK2-encoding nucleotide sequences possessing a substantially different codon usage. Codons can be selected to increase the rate at which expression of the peptide occurs in a particular prokaryotic or eukaryotic expression host in accordance with the frequency with which particular codons are utilized by the host. Other reasons for substantially altering the nucleotide sequence encoding the HJAK2 without altering the encoded amino acid sequence include the production of RNA transcripts having more desirable properties, such as a longer half-life, than transcripts produced from the naturally occurring sequence.

Nucleotide sequences encoding HJAK2 may be joined to a variety of other nucleotide sequences by means of well established recombinant DNA techniques (Sambrook J et al (1989) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor N.Y., Chapters 4, 8, 16 and 17; or Ausubel F M et al (1989) Current Protocols in Molecular Biology, John Wiley & Sons, New York, N.Y., Chapters 9, 13, and 16). useful sequences for joining to hjak2 include an assortment of cloning vectors such as plasmids, cosmids, lambda phage derivatives, phagemids, and the like. Vectors of interest include vectors for replication, expression, probe generation, sequencing, and the like. In general, vectors of interest may contain an origin of replication functional in at least one organism, convenient restriction endonuclease sensitive sites, and selectable markers for one or more host cell systems.

PCR as described in U.S. Pat. Nos. 4,683,195; 4,800,195; and 4,965,188, provides additional uses for oligonucleotides based upon the hjak2 nucleotide sequence. Such oligomers are generally chemically synthesized, but they may be of recombinant origin or a mixture of both. Oligomers generally comprise two nucleotide sequences, one with sense orientation 5′->3′) and one with antisense orientation (3′ to 5′) employed under optimized conditions for identification of a specific gene or diagnostic use. The same two oligomers, nested sets of oligomers, or even a degenerate pool of oligomers may be employed under less stringent conditions for identification and/or quantitation of closely related DNA or RNA sequences.

Full length genes may be cloned utilizing partial nucleotide sequence and various methods known in the art. Sarkar et al (1993; PCR Methods Applic 2:318-22) disclose “restriction-site PCR” as a direct method which uses universal primers to retrieve unknown sequence adjacent to a known locus. First, genomic DNA is amplified in the presence of primer to linker and a primer specific to the known region. The amplified sequences are subjected to a second round of PCR with the same linker primer and another specific primer internal to the first one. Products of each round of PCR are transcribed with an appropriate RNA polymerase and sequenced using reverse transcriptase. Sarkar et al present data concerning Factor IX for which they identified a conserved stretch of 20 nucleotides in the 3′ noncoding region of the gene.

Inverse PCR is the first method to report successful acquisition of unknown sequences starting with primers based on a known region (Triglia T et al (1988) Nucleic Acids Res 16:8186). The method uses several restriction enzymes to generate a suitable fragment in the known region of a gene. The fragment is then circularized by intramolecular ligation and used as a PCR template. Divergent primers are designed from the known region. The multiple rounds of restriction enzyme digestions and ligations that are necessary prior to PCR make the procedure slow and expensive (Sarkar et al, supra).

Capture PCR (Lagerstrom Metal (1991) PCR MethodsApplic 1:111-19) is a method for PCR amplification of DNA fragments adjacent to a known sequence in human and YAC DNA. As noted by Gobinda et al (supra), capture PCR also requires multiple restriction enzyme digestions and ligations to place an engineered double-stranded sequence into an unknown portion of the DNA molecule before PCR. Although the restriction and ligation reactions are carried out simultaneously, the requirements for extension, immobilization and two rounds of PCR and purification prior to sequencing render the method cumbersome and time consuming.

Parker J D et al (1991; Nucleic Acids Res 19:3055-60), teach walking PCR, a method for targeted gene walking which permits retrieval of unknown sequence. In this same vein, PROMOTERFINDER a new kit available from Clontech (Palo Alto Calif.) uses PCR and primers derived from p53 to walk in genomic DNA. Nested primers and special PromoterFinder libraries are used to detect upstream sequences such as promoters and regulatory elements. This process avoids the need to screen libraries and is useful in finding intron/exon junctions.

Another new PCR method, “Improved Method for Obtaining Full Length cDNA Sequences” by Guegler et al, patent application Ser. No. 08/487,112, filed Jun. 7, 1995 and hereby incorporated by reference, employs XL-PCR (Perkin-Elmer, Foster City Calif.) to amplify and extend partial nucleotide sequence into longer pieces of DNA. This method was developed to allow a single researcher to process multiple genes (up to 20 or more) at one time and to obtain an extended (possibly full-length) sequence within 6-10 days. This new method replaces methods which use labelled probes to screen plasmid libraries and allow one researcher to process only about 3-5 genes in 14-40 days.

In the first step, which can be performed in about two days, any two of a plurality of primers are designed and synthesized based on a known partial sequence. In step the second step, which takes about six to eight hours, the sequence is extended by PCR amplification of a selected library. The third and fourth steps, which take about one day, are purification of the amplified cDNA and its ligation into an appropriate vector. The fifth step, which takes about one day, involves transforming and growing up host bacteria. The sixth step, which takes approximately five hours, PCR is used to screen bacterial clones for extended sequence. The final steps, which take about one day, involve the preparation and sequencing of selected clones.

If the full length cDNA has not been obtained, the entire procedure is repeated using either the original library or some other preferred library. The preferred library may be one that has been size-selected to include only larger cDNAs or may consist of single or combined commercially available libraries, eg. lung, liver, heart and brain from Gibco/BRL (Gaithersburg Md.). The cDNA library may have been prepared with oligo (dT) or random priming. Random primed libraries are preferred in that they will contain more sequences which contain 5′ ends of genes. A randomly primed library may be particularly useful if an oligo (dT) library does not yield a complete gene. It must be noted that the larger and more complex the protein, the less likely it is that the complete gene will be found in a single plasmid.

A new method for analyzing either the size or the nucleotide sequence of PCR products is capillary electrophoresis. Systems for rapid sequencing are available from Perkin Elmer (Foster City Calif.), Beckman Instruments (Fullerton Calif.), and other companies. Capillary sequencing employs flowable polymers for electrophoretic separation, four different fluorescent dyes (one for each nucleotide) which are laser activated, and detection of the emitted wavelengths by a charge coupled device camera. Output/light intensity is converted to electrical signal using appropriate software (eg. GENOTYPER and SEQUENCE NAVIGATOR from Perkin Elmer) and the entire process from loading of samples to computer analysis and electronic data display is computer controlled. Capillary electrophoresis provides greater resolution and is many times faster than standard gel based procedures. It is particularly suited to the sequencing of small pieces of DNA which might be present in limited amounts in a particular sample. The reproducible sequencing of up to 350 bp of M13 phage DNA in 30 min has been reported (Ruiz-Martinez M C et al (1993) Anal Chem 65:2851-8).

Another aspect of the subject invention is to provide for hjak2 hybridization probes which are capable of hybridizing with naturally occurring nucleotide sequences encoding HJAK2. The stringency of the hybridization conditions will determine whether the probe identifies only the native nucleotide sequence of hjak2 or sequences of other closely related Jak2 kinase molecules. If degenerate hjak2 nucleotide sequences of the subject invention are used for the detection of related kinase encoding sequences, they should preferably contain at least 50% of the nucleotides of the sequences presented herein. Hybridization probes of the subject invention may be derived from the nucleotide sequence presented in SEQ ID NO: 1 or from surrounding genomic sequences comprising untranslated regions such as promoters, enhancers and introns. Such hybridization probes may be labelled with appropriate reporter molecules.

Means for producing specific hybridization probes for this Jak2 kinase include oligolabelling, nick translation, end-labelling or PCR amplification using a labeled nucleotide. Alternatively, the cDNA sequence may be cloned into a vector for the production of an mRNA probe. Such vectors are known in the art, are commercially available, and may be used to synthesize RNA probes in vitro by addition of an appropriate RNA polymerase such as T7, T3 or SP6 and labelled nucleotides. A number of companies (such as Pharmacia Biotech, Piscataway N.J.; Promega, Madison Wis.; US Biochemical Corp, Cleveland, Ohio; etc.) supply commercial kits and protocols for these procedures.

It is also possible to produce a DNA sequence, or portions thereof, entirely by synthetic chemistry. Sometimes the source of information for producing this sequence comes from the known homologous sequence from closely related organisms. After synthesis, the nucleic acid sequence can be used alone or joined with a pre-existing sequence and inserted into one of the many available DNA vectors and their respective host cells using techniques well known in the art. Moreover, synthetic chemistry may be used to introduce specific mutations into the nucleotide sequence. Alternatively, a portion of sequence in which a mutation is desired can be synthesized and recombined with a portion of an existing genomic or recombinant sequence.

Hjak2 nucleotide sequence can be used in a diagnostic test or assay to detect disorder or disease processes associated with abnormal expression of hjak2. The nucleotide sequence is added to a sample (fluid, cell or tissue) from a patient under hybridizing conditions. After an incubation period, the sample is washed with a compatible fluid which optionally contains a reporter molecule which will bind the specific nucleotide. After the compatible fluid is rinsed off, the reporter molecule is quantitated and compared with a standard for that fluid, cell or tissue. If hjak2 expression is significantly different from the standard, the assay indicates the presence of disorder or disease. The form of such qualitative or quantitative methods may include northern analysis, dot blot or other membrane-based technologies, dip stick, pin or chip technologies, PCR, ELISAs or other multiple sample format technologies.

This same assay, combining a sample with the nucleotide sequence, is applicable in evaluating the efficacy of a particular therapeutic treatment regime. It may be used in animal studies, in clinical trials, or in monitoring the treatment of an individual patient. First, standard expression must be established for use as a basis of comparison. Second, samples from the animals or patients affected by a disorder or disease are combined with the nucleotide sequence to evaluate the deviation from the standard or normal profile. Third, an entirely new or pre-existing therapeutic agent is administered, and a treatment profile is generated. This posat-treatment assay is evaluated to determine whether the patient profile progresses toward or returns to the standard pattern. Successive treatment profiles may be used to show the efficacy of treatment over a period of several days or several months.

The nucleotide sequence for hjak2 can also be used to generate probes for mapping native genomic sequence. The sequence may be mapped to a particular chromosome or to a specific region of the chromosome using well known techniques. These include in situ hybridization to chromosomal spreads (Verma et al (1988) Human Chromosomes: A Manual of Basic Techniques, Pergamon Press, New York City), flow-sorted chromosomal preparations, or artificial chromosome constructions such as yeast artificial chromosomes (YACs), bacterial artificial chromosomes (BACs), bacterial P1 constructions or single chromosome cDNA libraries.

In situ hybridization of chromosomal preparations and physical mapping techniques such as linkage analysis using established chromosomal markers are invaluable in extending genetic maps. Examples of such genetic maps can regularly be found in the journal Science (eg, 1994; 265:1981f). Often the placement of a gene on the chromosome of another mammalian species may reveal associated markers even if the number or arm of a particular human chromosome is not known. New sequences can be assigned to chromosomal arms, or parts thereof, by physical mapping. This provides valuable information to investigators searching for disease genes using positional cloning or other gene discovery techniques. Once a disease or syndrome, such as ataxia telangiectasia (AT), has been crudely localized by genetic linkage to a particular genomic region, for example, AT to 11q22-23 (Gatti et al (1988) Nature 336:577-580), any sequences mapping to that area may represent associated or regulatory genes for further investigation. The nucleotide sequence of the subject invention may also be used to detect differences in the chromosomal location due to translocation, inversion, etc. between normal and carrier or affected individuals.

The nucleotide sequence encoding HJAK2 may be used to produce an amino acid sequence using well known methods of recombinant DNA technology. Goeddel (1990, Gene Expression Technology, Methods and Enzymology, Vol 185, Academic Press, San Diego Calif.) is one among many publications which teach expression of an isolated, purified nucleotide sequence. The amino acid or peptide may be expressed in a variety of host cells, either prokaryotic or eukaryotic. Host cells may be from the same species from which the nucleotide sequence was derived or from a different species. Advantages of producing an amino acid sequence or peptide by recombinant DNA technology include obtaining adequate amounts for purification and the availability of simplified purification procedures.

Cells transformed with hjak2 nucleotide sequence may be cultured under conditions suitable for the expression and recovery of peptide from cell culture. The peptide produced by a recombinant cell may be secreted or may be contained intracellularly depending on the sequence and/or the vector used. In general, it is more convenient to prepare recombinant proteins in secreted form, and this is accomplished by ligating hjak2 to a recombinant nucleotide sequence which directs its movement through a particular prokaryotic or eukaryotic cell membrane. Other recombinant constructions may join hjak2 to nucleotide sequence encoding a polypeptide domain which will facilitate protein purification (Kroll D J et al (1993) DNA Cell Biol 12:441-53).

Direct peptide synthesis using solid-phase techniques (Creighton (1983) Proteins Structures And Molecular Principles, WH Freeman and Co., New York N.Y. pp. 50-60) is an alternative to recombinant or chimeric peptide production. Automated synthesis may be achieved, for example, using Applied Biosystems 431A peptide synthesizer in accordance with the instructions provided by the manufacturer. Additionally HJAK2 or any part thereof may be mutated during direct synthesis and combined using chemical methods with other kinase sequences, or parts thereof.

Although an amino acid sequence or oligopeptide used for antibody induction does not require biological activity, it must be immunogenic. HJAK2 used to induce specific antibodies may have an amino acid sequence consisting of at least five amino acids and preferably at least 10 amino acids. Short stretches of amino acid sequence may be fused with those of another protein such as keyhole limpet hemocyanin, and the chimeric peptide used for antibody production. Alternatively, the peptide may be of sufficient length to contain an entire domain.

Antibodies specific for HJAK2 may be produced by inoculation of an appropriate animal with an antigenic fragment of the peptide. An antibody is specific for HJAK2 if it is produced against an epitope of the polypeptide and binds to at least part of the natural or recombinant protein. Antibody production includes not only the stimulation of an immune response by injection into animals, but also analogous processes such as the production of synthetic antibodies, the screening of recombinant immunoglobulin libraries for specific-binding molecules (Orlandi R et al (1989) PNAS 86:3833-3837, or Huse W D et al (1989) Science 256:1275-1281), or the in vitro stimulation of lymphocyte populations. Current technology (Winter G and Milstein C (1991) Nature 349:293-299) provides for a number of highly specific binding reagents based on the principles of antibody formation. These techniques may be adapted to produce molecules which specifically bind HJAK2. Antibodies or other appropriate molecules generated against a specific immunogenic peptide fragment or oligopeptide can be used in Western analysis, enzyme-linked immunosorbent assays (ELISA) or similar tests to establish the presence of or to quantitate amounts of HJAK2 active in normal, diseased, or therapeutically treated cells or tissues.

The examples below are provided to illustrate the subject invention. These example; are provided by way of illustration and are not included for the purpose of limiting the invention.

EXAMPLES

I Placenta cDNA Library Construction

The cDNa library was constructed from normal placenta. The tissue was lysed in a buffer containing guanidinium isothiocyanate. The lysate was extracted with phenol chloroform and precipitated with ethanol. Poly A⁺ RNA was isolated using biotinylated oligo d(T) primer and steptavidin coupled to a paramagnetic particle (Promega Corp. Madison Wis.) and sent to Stratagene (La Jolla Calif.) for cDNA library preparation. The cDNA synthesis was primed using both oligo d(T) and random hexamers, and the two cDNA libraries were treated separately. Synthetic adapter oligonucleotides were ligated onto the ends of the cDNAs which were digested with XhoI and inserted into the UNIZAP vector system (Stratagene).

The PBLUESCRIPT phagemid (Stratagene) was excised from each library and phagemids from the two cDNA libraries were combined into a single library by mixing equal numbers of bacteriophage. The phagemids were transformed into E. coli host strain XL1-BLUE (Stratagene). Enzymes from both PBLUESCRIPT and a cotransformed f1 helper phage nicked the DNA, initiated new DNA synthesis, and created the smaller, single-stranded circular plasmid DNA molecules which contained the cDNA insert. The plasmid DNA was released, purified, and used to reinfect fresh host cells (SOLR, Stratagene). Presence of the β-lactamase gene on the plasmid allowed transformed bacteria to grow on medium containing ampicillin.

II Isolation of cDNA Clones

Plasmid DNAs containing the cDNA insert were purified using the QIAWELL-8 plasmid purification system from QIAGEN Inc (Chatsworth Calif.) according to standard protocol. The DNA was eluted and prepared for DNA sequencing and other analytical manipulations.

The cDNA inserts from random isolates of the placenta library were partially sequenced. The cDNAs were sequenced by the method of Sanger F and A R Coulson (1975; J Mol Biol 94:441f), using a CATALYST 800 or a Hamilton MICRO LAB 2200 (Hamilton, Reno Nev.) in combination with four Peltier thermal cyclers (PTC200 from MJ Research, Watertown Mass.) and Applied Biosystems 377 or 373 DNA sequencing systems (Perkin Elmer), and reading frame was determined.

III Sequencing of cDNA Clones

The cDNA inserts from random isolates of the placenta library were sequenced in part. Methods for DNA sequencing are well known in the art and employ such enzymes as the Klenow fragment of DNA polymerase I, SEQUENASE (US Biochemical Corp.) or Taq polymerase. Methods to extend the DNA from an oligonucleotide primer annealed to the DNA template of interest have been developed for both single- and double-stranded templates. Chain termination reaction products were separated using electrophoresis and detected via their incorporated, labelled precursors. Recent improvements in mechanized reaction preparation, sequencing and analysis have permitted expansion in the number of sequences that can be determined per day. Preferably, the process is automated with machines such as the MICRO LAB 2200 (Hamilton, Reno Nev.), Peltier thermal cycler (PTC200; MJ Research, Watertown Mass.) and the Applied Biosystems CATALYST 800 and 377 and 373 DNA sequencers.

The quality of any particular cDNA library may be determined by performing a pilot scale analysis of the cDNAs and checking for percentages of clones containing vector, lambda or E. coli DNA, mitochondrial or repetitive DNA, and clones with exact or homologous matches to public databases. The number of unique sequences, those having no known match in any available database, are then recorded.

IV Homology Searching of cDNA Clones and Their Deduced Proteins

Each sequence so obtained was compared to sequences in GenBank using a search algorithm developed by Applied Biosystems and incorporated into the INHERIT™ 670 Sequence Analysis System. In this algorithm, Pattern Specification Language (TRW Inc, Los Angeles Calif.) was used to determine regions of homology. The three parameters that determine how the sequence comparisons run were window size, window offset, and error tolerance. Using a combination of these three parameters, the DNA database was searched for sequences containing regions of homology to the query sequence, and the appropriate sequences were scored with an initial value. Subsequently, these homologous regions were examined using dot matrix homology plots to distinguish regions of homology from chance matches. Smith-Waterman alignments were used to display the results of the homology search.

Peptide and protein sequence homologies were ascertained using the INHERIT 670 Sequence Analysis System in a way similar to that used in DNA sequence homologies. Pattern Specification Language and parameter windows were used to search protein databases for sequences containing regions of homology which were scored with an initial value. Dot-matrix homology plots were examined to distinguish regions of significant homology from chance matches.

Alternatively, BLAST, which stands for Basic Local Alignment Search Tool, is used to search for local sequence alignments (Altschul S F (1993) J Mol Evol 36:290-300; Altschul, S F et al (1990) J Mol Biol 215:403-10). BLAST produces alignments of both nucleotide and amino acid sequences to determine sequence similarity. Because of the local nature of the alignments, BLAST is especially useful in determining exact matches or in identifying homologs. While it is useful for matches which do not contain gaps, it is inappropriate for performing motif-style searching. The fundamental unit of BLAST algorithm output is the High-scoring Segment Pair (HSP).

An HSP consists of two sequence fragments of arbitrary but equal lengths whose alignment is locally maximal and for which the alignment score meets or exceeds a threshold or cutoff score set by the user. The BLAST approach is to look for HSPs between a query sequence and a database sequence, to evaluate the statistical significance of any matches found, and to report only those matches which satisfy the user-selected threshold of significance. The parameter E establishes the statistically significant threshold for reporting database sequence matches. E is interpreted as the upper bound of the expected frequency of chance occurrence of an HSP (or set of HSPs) within the context of the entire database search. Any database sequence whose match satisfies E is reported in the program output.

The partial hjak2 molecule presented and claimed in this application was identified using the criteria above. The full length nucleic and amino acid sequences for this novel human Jak2 kinase are shown in FIGS. 1A-1H. FIGS. 2A-2E show the alignment between the translated amino acid sequence for hjak2 and the closest related molecule, murine Jak2 kinase (MUSPTK1; GenBank GI 409584; Wilks A F (1989) Proc Nat Acad Sci 86:1603-7).

V Extension of cDNAs to Full Length

The partial sequence originally identified in Incyte Clone 179527 was used to design oligonucleotide primers for extension of the cDNAs to full length. Primers are designed based on known sequence; one primer is synthesized to initiate extension in the antisense direction (XLR) and the other to extend sequence in the sense direction (XLF). The primers allow the sequence to be extended “outward” generating amplicons containing new, unknown nucleotide sequence for the gene of interest. The primers may be designed using OLIGO 4.0 (National Biosciences Inc, Plymouth Minn.), or another appropriate program, to be 22-30 nucleotides in length, to have a GC content of 50% or more, and to anneal to the target sequence at temperatures about 68°-72° C. Any stretch of nucleotides which would result in hairpin structures and primer-primer dimerizations was avoided.

The placenta cDNA library was used with XLR (SEQ ID NO: 4) and XLF (SEQ ID NO: 5) primers to extend and amplify Incyte Clone 179527 to obtain the full length Jak2 kinase sequence.

By following the instructions for the XL-PCR kit and thoroughly mixing the enzyme and reaction mix, high fidelity amplification is obtained. Beginning with 40 pmol of each primer and the recommended concentrations of all other components of the kit, PCR is performed using the Peltier thermal cycler (PTC200; MJ Research, Watertown Mass.) and the following parameters: Step 1 94° C. for 1 min (initial denaturation) Step 2 65° C. for 1 min Step 3 68° C. for 6 min Step 4 94° C. for 15 sec Step 5 65° C. for 1 min Step 6 68° C. for 7 min Step 7 Repeat step 4-6 for 15 additional cycles Step 8 94° C. for 15 sec Step 9 65° C. for 1 min Step 10 68° C. for 7:15 min Step 11 Repeat step 8-10 for 12 cycles Step 12 72° C. for 8 min Step 13 4° C. (and holding)

A 5-10 μl aliquot of the reaction mixture is analyzed by electrophoresis on a low concentration (about 0.6-0.8%) agarose mini-gel to determine which reactions were successful in extending the sequence. Although all extensions potentially contain a full length gene, some of the largest products or bands are selected and cut out of the gel. Further purification involves using a commercial gel extraction method such as QIAQUICK (QIAGEN Inc). After recovery of the DNA, Klenow enzyme is used to trim single-stranded, nucleotide overhangs creating blunt ends which facilitate religation and cloning.

After ethanol precipitation, the products are redissolved in 13 μl of ligation buffer. Then, 1 μl T4-DNA ligase (15 units) and 1 μl T4 polynucleotide kinase are added, and the mixture is incubated at room temperature for 2-3 hours or overnight at 16° C. Competent E. coli cells (in 40 μl of appropriate media) are transformed with 3 μl of ligation mixture and cultured in 80 μl of SOC medium (Sambrook J et al, supra). After incubation for one hour at 37° C. the whole transformation mixture is plated on Luria Bertani (LB)-agar (Sambrook J et al, supra) containing 2×Carb. The following day, 12 colonies are randomly picked from each plate and cultured in 150 μl of liquid LB/2×Carb medium placed in an individual well of an appropriate, commercially-available, sterile 96-well microtiter plate. The following day, 5 μl of each overnight culture is transferred into a non-sterile 96-well plate and after dilution 1:10 with water, 5 μl of each sample is transferred into a PCR array.

For PCR amplification, 18 μl of concentrated PCR reaction mix (3.3×) containing 4 units of rTth DNA polymerase, a vector primer and one or both of the gene specific primers used for the extension reaction are added to each well. Amplification is performed using the following conditions: Step 1 94° C. for 60 sec Step 2 94° C. for 20 sec Step 3 55° C. for 30 sec Step 4 72° C. for 90 sec Step 5 Repeat steps 2-4 for an additional 29 cycles Step 6 72° C. for 180 sec Step 7 4° C. (and holding)

Aliquots of the PCR reactions are run on agarose gels together with molecular weight markers. The sizes of the PCR products are compared to the original partial cDNAs, and appropriate clones are selected, ligated into plasmid and sequenced.

VI Diagnostic Assay Using Hjak2 Specific Oligomers

In those cases where a specific condition (see definitions, supra) is suspected to involve expression of altered quantities of hjak2, oligomers may be designed to establish the presence and/or quantity of mRNA expressed in a biological sample. There are several methods currently being used to quantitate the expression of a particular molecule. Most of these methods use radiolabelled (Melby P C et al 1993 J Immunol Methods 159:235-44) or biotinylated (Duplaa C et al 1993 Anal Biochem 212:229-36) nucleotides, coamplification of a control nucleic acid, and standard curves onto which the experimental results are interpolated. Quantitation may be speeded up by running the assay in an ELISA format where the oligomer-of-interest is presented in various dilutions and a calorimetric response gives rapid quantitation. For example, a complete HJAK2 deficiency may result in the inability to undergo cell division or to react to an infectious organism. In like manner, overexpression may cause major inflammation, swelling and major tissue damage. In either case, a quick diagnosis may allow health professionals to treat the condition and prevent worsening of the condition. This same assay can be used to monitor progress of the patient as his/her physiological situation moves toward the normal range during therapy.

VII Sense or Antisense Molecules

Knowledge of the correct cDNA sequence of this Jak2 kinase or its regulatory elements enable its use as a tool in sense (Youssoufian H and H F Lodish 1993) Mol Cell Biol 13:98-104) or antisense (Eguchi et al (1991) Annu Rev Biochem 60:631-652) technologies for the investigation or alteration of gene expression. To inhibit in vivo or in vitro cdp expression, an oligonucleotide based on the coding sequence of an hjak2 designed with OLIGO 4.0 (National Biosciences Inc) is used. Alternatively, a fragment of an hjak2 is produced by digesting hjak2 coding sequence with restriction enzymes. These enzymes and specific restrictions sites may be selected using INHERIT Analysis software (Applied Biosystems), and the strands separated by heating the fragments and selecting for the antisense strand. Either the oligonucleotide or the fragment may be used to inhibit hjak2 expression. Furthermore, antisense molecules can be designed to inhibit promoter binding in the upstream nontranslated leader or at various sites along the hjak2 coding region. Alternatively, antisense molecules may be designed to inhibit translation of an mRNA into polypeptide by preparing an oligomer or fragment which will bind in the region spanning approximately −10 to +10 nucleotides at the 5′ end of the coding sequence. These technologies are now well known to those of in the art.

In addition to using antisense molecules constructed to interrupt transcription of the open reading frame, modifications of gene expression can be obtained by designing antisense sequences to enhancers, introns, or even to trans-acting regulatory genes. Similarly, inhibition can be achieved using Hogeboom base-pairing methodology, also known as “triple helix” base pairing. Triple helix pairing compromises the ability of the double helix to open sufficiently for the binding of polymerases, transcription factors, or regulatory molecules.

Any of these types of antisense molecules may be placed in expression vectors and used to transform preferred cells or tissues. This may include introduction of the expression vector into an organ, a tumor, a synovial cavity or the vascular system for transient or short term therapy or introduction via gene therapy technologies for long term treatment. Transient expression may last for a month or more with a non-replicating vector and for three months or more if appropriate replication elements are used in the transformation or expression system.

Stable transformation of appropriate dividing cells with a vector containing the antisense molecule can produce a transgenic cell line, tissue, or organism (see, for example, Trends in Biotechnol 11:155-215 (1993) and U.S. Pat. No. 4,736,866, 12 Apr. 1988). Those cells which assimilate or replicate enough copies of the vector to allow stable integration will also produce enough antisense molecules to compromise or entirely eliminate normal activity of the hjak2. Frequently, the function of an hjak2 can be ascertained by observing behaviors such as lethality, loss of a physiological pathway, changes in morphology, etc. at the cellular, tissue, or organismal level.

VIII Expression of HJAK2

Expression of the HJAK2 may be accomplished by subcloning the cDNA into appropriate vectors and transfecting the vectors into host cells. In this case, the cloning vector previously used for the generation of the tissue library also provides for direct expression of the hjak2 sequence in E. coli. Upstream of the cloning site, this vector contains a promoter for β-galactosidase, followed by sequence containing the amino-terminal Met and the subsequent 7 residues of β-galactosidase. Immediately following these eight residues is a bacteriophage promoter useful for transcription and a linker containing a number of unique restriction sites.

Induction of an isolated, transfected bacterial strain with IPTG using standard methods will produce a fusion protein corresponding to the first seven residues of β-galactosidase, about 5 to 15 residues which correspond to linker, and the peptide encoded within the hjak2 cDNA. Since cDNA clone inserts are generated by an essentially random process, there is one chance in three that the included cDNA will lie in the correct frame for proper translation. If the cDNA is not in the proper reading frame, it can be obtained by deletion or insertion of the appropriate number of bases by well known methods including in vitro mutagenesis, digestion with exonuclease III or mung bean nuclease, or oligonucleotide linker inclusion.

The cDNA can be shuttled into other vectors known to be useful for expression of protein in specific hosts. Oligonucleotide linkers containing cloning sites as well as a stretch of DNA sufficient to hybridize to the end of the target cDNA (25 bases) can be synthesized chemically by standard methods. These primers can then be used to amplify the desired gene fragments by PCR. The resulting fragments can be digested with appropriate restriction enzymes under standard conditions and isolated by gel electrophoresis. Alternatively, similar gene fragments can be produced by digestion of the cDNA with appropriate restriction enzymes and filling in the missing gene sequence with chemically synthesized oligonucleotides. Partial nucleotide sequence from more than one kinase homolog can be ligated together and cloned into appropriate vectors to optimize expression.

Suitable expression hosts for such chimeric molecules include but are not limited to mammalian cells such as Chinese Hamster Ovary (CHO) and human 293 cells, insect cells such as Sf9 cells, yeast cells such as Saccharomyces cerevisiae, and bacteria such as E. coli. For each of these cell systems, a useful expression vector may also include an origin of replication to allow propagation in bacteria and a selectable marker such as the β-lactamase antibiotic resistance gene to allow selection in bacteria. In addition, the vectors may include a second selectable marker such as the neomycin phosphotransferase gene to allow selection in transfected eukaryotic host cells. Vectors for use in eukaryotic expression hosts may require RNA processing elements such as 3′ polyadenylation sequences if such are not part of the cDNA of interest.

If native promoters are not part of the cDNA, other host specific promoters may be specifically combined with the coding region of hjak2. They include MMTV, SV40, and metallothionine promoters for CHO cells; trp, lac, tac and T7 promoters for bacterial hosts; and alpha factor, alcohol oxidase and PGH promoters for yeast. In addition, transcription enhancers, such as the rous sarcoma virus (RSV) enhancer, may be used in mammalian host cells. Once homogeneous cultures of recombinant cells are obtained through standard culture methods, large quantities of recombinantly produced peptide can be recovered from the conditioned medium and analyzed using methods known in the art.

IX Isolation of Recombinant HJAK2

HJAK2 may be expressed as a recombinant protein with one or more additional polypeptide domains added to facilitate protein purification. Such purification facilitating domains include, but are not limited to, metal chelating peptides such as histidine-tryptophan modules that allow purification on immobilized metals, protein A domains that allow purification on immobilized immunoglobulin, and the domain utilized in the FLAGS extension/affinity purification system (Immunex Corp, Seattle Wash.). The inclusion of a cleavable linker sequence such as Factor XA or enterokinase (Invitrogen) between the purification domain and the hjak2 sequence may be useful to facilitate expression of HJAK2.

X Testing HJAK2 Activity

The sequence for HJAK2 in this application present many different domains (and subdomains as detailed in the background of the invention) which may be utilized: 1) individually for the production of antibodies, 2) in functional groups (eg. to span a membrane), and 3) as interchangeable, usable parts of a chimeric kinase. For example, a known, full length kinase such as the hjak2 kinase of this application may be used to swap related portions of the nucleic acid sequence, analogous to domains or subdomains of MAP kinase polypeptides. The chimeric nucleotides, so produced, may be introduced into prokaryotic host cells (as reviewed in Strosberg A D and Marullo S (1992) Trends Pharma Sci 13:95-98) or eukaryotic host cells. These host cells are then employed in procedures to determine what molecules activate the kinase or what molecules are activated by a kinase. Such activating or activated molecules may be of extracellular, intracellular, biologic or chemical origin.

An example of a test system, in this case for hjak2 kinase, can be based on the interaction of protein tyrosine kinases with chemokine receptors (Taniguchi T (1995) Science 268:251-255). These receptors are capable of activating a variety of nonreceptor protein tyrosine kinases when stimulated by an extracellular chemokine. C—X—C chemokines such as platelet factor 4, interleukin-8, connective tissue activating protein III, neutrophil activating peptide 2, are soluble activators of neutrophils.

A standard measure of neutrophil activation involves measuring the mobilization of Ca⁺⁺ as part of the signal transduction pathway. The experiment involves several steps. First, blood cells obtained from venipuncture are fractionated by centrifugation on density gradients. Enriched populations of neutrophils are further fractionated on columns by negative selection using antibodies specific for other blood cells types. Next, neutrophils are transformed with an expression vector containing the kinase nucleic acid sequence of interest and preloaded fluorescent probe whose emission characteristics have been altered by Ca⁺⁺ binding. Or in the alternative, the neutrophil is preloaded with the purified kinase of interest and fluorescent probe. Then, when the cells are exposed to an appropriate chemokine, the chemokine receptor activates the kinase which, in turn, initiates Ca⁺⁺ flux. Ca⁺⁺ mobilization is observed and measured using fluorometry as has been described in Grynkievicz G et al (1985) J Biol Chem 260:3440, and McColl S et al (1993) J Immunol 150:4550-4555, incorporated herein by reference.

XI Identification of or Production of HJAK2 Specific Antibodies

Purified HJAK2 is used to screen a pre-existing antibody library or to raise antibodies using either polyclonal or monoclonal methodology. In a polyclonal approach, denatured protein from the reverse phase HPLC separation is obtained in quantities up to 75 mg. This denatured protein can be used to immunize mice or rabbits using standard protocols; about 100 micrograms are adequate for immunization of a mouse, while up to 1 mg might be used to immunize a rabbit. For identifying mouse hybridomas, the denatured protein can be radioiodinated and used to screen potential murine B-cell hybridomas for those which produce antibody. This procedure requires only small quantities of protein, such that 20 mg would be sufficient for labeling and screening of several thousand clones.

In a monoclonal approach, the amino acid sequence of HJAK2, as deduced from translation of the cDNA, is analyzed to determine regions of high immunogenicity. Oligopeptides comprising appropriate hydrophilic regions are synthesized and used in suitable immunization protocols to raise antibodies. Analysis to select appropriate epitopes is described by Ausubel F M et al (supra). The optimal amino acid sequences for immunization are usually at the C-terminus, the N-terminus, and intervening, hydrophilic regions of the polypeptide which are likely to be exposed to the external environment when the protein is in its natural conformation.

Typically, selected peptides of about 15 residues in length are synthesized using an Applied Biosystems 431A peptide synthesizer using fmoc-chemistry and coupled to keyhole limpet hemocyanin (KLH, Sigma) by reaction with M-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS; Ausubel F M et al, supra). If necessary, a cysteine may be introduced at the N-terminus of the peptide to permit coupling to KLH. Rabbits are immunized with the peptide-KLH complex in complete Freund's adjuvant. The resulting antisera are tested for antipeptide activity by binding the peptide to plastic, blocking with 1% BSA, reacting with antisera, washing and reacting with labeled (radioactive or fluorescent), affinity purified, specific goat anti-rabbit IgG.

Hybridomas may also be prepared and screened using standard techniques. Hybridomas of interest are detected by screening with labeled HJAK2 to identify those fusions producing the monoclonal antibody with the desired specificity. In a typical protocol, wells of plates (FAST; Becton-Dickinson, Palo Alto, Calif.) are coated with affinity purified, specific rabbit-anti-mouse antibodies (or suitable anti-species Ig) at 10 mg/ml. The coated wells are blocked with 1% BSA, washed and exposed to supernatants from hybridomas. After incubation the wells are exposed to labeled HJAK2, 1 mg/ml. Clones producing antibodies will bind a quantity of labeled HJAK2 which is detectable above background. Such clones are expanded and subjected to 2 cycles of cloning at limiting dilution (1 cell/3 wells). Cloned hybridomas are injected into pristine mice to produce ascites, and monoclonal antibody is purified from mouse ascitic fluid by affinity chromatography on Protein A. Monoclonal antibodies with affinities of at least 10⁸/M, preferably 10⁹ to 10¹⁰ or stronger, will typically be made by standard procedures as described in Harlow and Lane (1988) Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor N.Y.; and in Goding (1986) Monoclonal Antibodies: Principles and Practice, Academic Press, New York City, both incorporated herein by reference.

XII Diagnostic Test Using HJAK2 Specific Antibodies

Particular HJAK2 antibodies are useful for the diagnosis of prepathologic conditions, and chronic or acute diseases which are characterized by differences in the amount or distribution of HJAK2. To date, HJAK2 has been found only in the placenta library; however, its activity there is most probably associated with organ function, inflammation or defense.

Diagnostic tests for HJAK2 include methods utilizing the antibody and a label to detect HJAK2 in human body fluids, tissues or extracts of such tissues. The polypeptides and antibodies of the present invention may be used with or without modification. Frequently, the polypeptides and antibodies will be labeled by joining them, either covalently or noncovalently, with a reporter molecule. A wide variety of labels and conjugation techniques are known and have been reported extensively in both the scientific and patent literature. Suitable reporter molecules or labels include those radionuclides, enzymes, fluorescent, chemiluminescent, or chromogenic agents previously mentioned as well as substrates, cofactors, inhibitors, magnetic particles and the like. Patents teaching the use of such labels include U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,227,437; 4,275,149; and 4,366,241. Also, recombinant immunoglobulins may be produced as shown in U.S. Pat. No. 4,816,567, incorporated herein by reference.

A variety of protocols for measuring soluble or membrane-bound HJAK2, using either polyclonal or monoclonal antibodies specific for the respective protein are known in the art. Examples include enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA) and fluorescent activated cell sorting (FACS). A two-site, monoclonal-based immunoassay utilizing monoclonal antibodies reactive to two non-interfering epitopes on HJAK2 is preferred, but a competitive binding assay may be employed. These assays are described, among other places, in Maddox, D E et al (1983, J Exp Med 158:1211).

XIII Purification of Native HJAK2 Using Specific Antibodies

Native or recombinant HJAK2 can be purified by immunoaffinity chromatography using antibodies specific for that particular HJAK2. In general, an immunoaffinity column is constructed by covalently coupling the anti-HJAK2 antibody to an activated chromatographic resin.

Polyclonal immunoglobulins are prepared from immune sera either by precipitation with ammonium sulfate or by purification on immobilized protein A (Pharmacia Biotech). Likewise, monoclonal antibodies are prepared from mouse ascites fluid by ammonium sulfate precipitation or chromatography on immobilized Protein A. Partially purified immunoglobulin is covalently attached to a chromatographic resin such as CnBr-activated SEPHAROSE (Pharmacia Biotech). The antibody is coupled to the resin, the resin is blocked, and the derivative resin is washed according to the manufacturer's instructions.

Such immunoaffinity columns may be utilized in the purification of HJAK2 by preparing a fraction from cells containing HJAK2 in a soluble form. This preparation may be derived by solubilization of whole cells or of a subcellular fraction obtained via differential centrifugation (with or without addition of detergent) or by other methods well known in the art. Alternatively, soluble HJAK2 containing a signal sequence may be secreted in useful quantity into the medium in which the cells are grown.

A soluble HJAK2-containing preparation is passed over the immunoaffinity column, and the column is washed under conditions that allow the preferential absorbance of HJAK2 (eg, high ionic strength buffers in the presence of detergent). Then, the column is eluted under conditions that disrupt antibody/HJAK2 binding (eg, a buffer of pH 2-3 or a high concentration of a chaotrope such as urea or thiocyanate ion), and HJAK2 is collected.

XIV Drug Screening

This invention is particularly useful for screening therapeutic compounds by using binding fragments of HJAK2 in any of a variety of drug screening techniques. The peptide fragment employed in such a test may either be free in solution, affixed to a solid support, borne on a cell surface or located intracellularly. One may measure, for example, the formation of complexes between HJAK2 and the agent being tested. Alternatively, one can examine the diminution in complex formation between HJAK2 and a receptor caused by the agent being tested.

Methods of screening for drugs or any other agents which can affect macrophage activation comprise contacting such an agent with HJAK2 fragment and assaying for the presence of a complex between the agent and the HJAK2 fragment. In such assays, the HJAK2 fragment is typically labelled. After suitable incubation, free HJAK2 fragment is separated from that present in bound form, and the amount of free or uncomplexed label is a measure of the ability of the particular agent to bind to HJAK2.

Another technique for drug screening provides high throughput screening for compounds having suitable binding affinity to the HJAK2 polypeptides and is described in detail in European Patent Application 84/03564, published on Sep. 13, 1984, incorporated herein by reference. Briefly stated, large numbers of different small peptide test compounds are synthesized on a solid substrate, such as plastic pins or some other surface. The peptide test compounds are reacted with fragment and washed. Bound HJAK2 fragment is then detected by methods well known in the art. Purified HJAK2 can also be coated directly onto plates for use in the aforementioned drug screening techniques. In addition, non-neutralizing antibodies can be used to capture the peptide and immobilize it on the solid support.

This invention also contemplates the use of competitive drug screening assays in which neutralizing antibodies capable of binding HJAK2 specifically compete with a test compound for binding to HJAK2 fragments. In this manner, the antibodies can be used to detect the presence of any peptide which shares one or more antigenic determinants with HJAK2.

XV Identification of Molecules which Interact with HJAK2

The inventive purified HJAK2 is a research tool for identification, characterization and purification of interacting molecules. Appropriate labels are incorporated into HJAK2 by various methods known in the art and HJAK2 is used to capture soluble or interact with membrane-bound molecules. A preferred method involves labeling the primary amino groups in HJAK2 with ¹²⁵I Bolton-Hunter reagent (Bolton, A E and Hunter, W M (1973) Biochem J 133: 529). This reagent has been used to label various molecules without concomitant loss of biological activity (Hebert C A et al (1991) J Biol Chem 266: 18989-94; McColl S et al (1993) J Immunol 150:4550-4555). Membrane-bound molecules are incubated with the labelled HJAK2 molecules, washed to removed unbound molecules, and the HJAK2 complex is quantified. Data obtained using different concentrations of HJAK2 are used to calculate values for the number, affinity, and association of HJAK2.

Labelled HJAK2 fragments are also useful as a reagent for the purification of molecules with which HJAK2 interacts, specifically including inhibitors. In one embodiment of affinity purification, HJAK2 is covalently coupled to a chromatography column. Cells and their membranes are extracted, HJAK2 is removed and various HJAK2-free subcomponents are passed over the column. Molecules bind to the column by virtue of their HJAK2 affinity. The HJAK2-complex is recovered from the column, dissociated and the recovered molecule is subjected to N-terminal protein sequencing or other identification procedure. If the captured molecule has an amino acid sequence, it can be used to design degenerate oligomers for use in cloning the gene from an appropriate cDNA library.

In an alternate method, monoclonal antibodies raised against HJAK2 fragments are screened to identify those which inhibit the binding of labelled HJAK2. These monoclonal antibodies are then used in affinity purification or expression cloning of associated molecules. Other soluble binding molecules are identified in a similar manner. Labelled HJAK2 is incubated with extracts or other appropriate materials derived from lung, kidney or other tissues with activated monocytes or macrophages. After incubation, HJAK2 complexes (which are larger than the lone HJAK2 fragment) are identified by a sizing technique such as size exclusion chromatography or density gradient centrifugation and are purified by methods well known in the art. The soluble binding protein(s) are subjected to N-terminal sequencing to obtain information sufficient for database identification, if the soluble protein is known, or for cloning, if the soluble protein is unknown.

XVI Use and Administration of Antibodies or Inhibitors to HJAK2

The antibodies and inhibitors can provide different effects when administered therapeutically. The antibodies and inhibitors are used to lessen or eliminate undue damage caused by disorders or diseases associated with upregulated HJAK2 expression. Each of these molecules or treatments (TSTs) will be formulated in a nontoxic, inert, pharmaceutically acceptable aqueous carrier medium preferably at a pH of about 5 to 8, more preferably 6 to 8, although the pH may vary according to the different characteristics of the peptide, antibody or inhibitor being formulated and the condition to be treated. Characteristics of TSTs include solubility of the molecule, half-life, antigenicity/immunogenicity and the ability of the inhibitor to reach its target(s). These and other characteristics may aid in defining an effective carrier. Native human proteins are preferred as TSTs, but recombinant peptides as well as organic or synthetic molecules resulting from drug screens may be equally effective in particular situations.

TSTs may be delivered by known routes of administration including but not limited to topical creams and gels; transmucosal spray and aerosol; transdermal patch and bandage; injectable, intravenous and lavage formulations; and orally administered liquids and pills particularly formulated to resist stomach acid and enzymes. The particular formulation, exact dosage, and route of administration will be determined by the attending physician and will vary according to each specific situation.

Such determinations are made by considering multiple variables such as the condition to be treated, the TST to be administered, and the pharmacokinetic profile of the particular TST. Additional factors which may be taken into account include disease state (eg. severity) of the patient, age, weight, gender, diet, time and frequency of administration, drug combination, reaction sensitivities, and tolerance/response to therapy. Long acting TST formulations might be administered every 3 to 4 days, every week, or once every two weeks depending on half-life and clearance rate of the particular TST.

Normal dosage amounts may vary from 0.1 to 100,000 micrograms, up to a total dose of about 1 g, depending upon the route of administration. Guidance as to particular dosages and methods of delivery is provided in the literature. See U.S. Pat. No. 4,657,760; 5,206,344; or 5,225,212. Those skilled in the art will employ different formulations for different TSTs. Administration to lung cells may necessitate delivery in a manner different from that to kidney or other cells.

It is contemplated that conditions associated with altered HJAK2 expression are treatable with TSTs. These conditions, which specifically include, but are not limited to, anemia, arteriosclerosis, asthma, bronchitis, emphysema, gingivitis, inflammatory bowel disease, insulin-dependent diabetes mellitus, leukemia, multiple endocrine neoplasias, osteoarthritis, osteoporosis, pulmonary fibrosis, rheumatoid arthritis, septic shock syndromes, and systemic lupus erythematosus may be specifically diagnosed by the tests discussed above. In addition, such tests may be used to monitor treatment.

All publications and patents mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described method and system of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the above-described modes for carrying out the invention which are obvious to those skilled in the field of molecular biology or related fields are intended to be within the scope of the following claims. 

1. An antibody that specifically binds to a polypeptide comprising an amino acid sequence of SEQ ID NO:2.
 2. The antibody of claim 1, wherein the antibody is polyclonal.
 3. The antibody of claim 1, wherein the antibody is monoclonal.
 4. The antibody of claim 1, wherein the antibody is recombinant.
 5. The antibody of claim 1, wherein the antibody is chimeric.
 6. The antibody of claim 1, wherein the antibody is human.
 7. The antibody of claim 1, wherein the antibody has an affinity for the polypeptide of at least about 10⁻⁹ M.
 8. The antibody of claim 7, wherein the antibody has an affinity for the polypeptide of at least about 10⁻¹⁰ M.
 9. The antibody of claim 8, further comprising a reporter molecule.
 10. The antibody of claim 14, wherein the reporter molecule is selected from the group consisting of radionuclides, enzymes, fluorescent agents, chemiluinescent agents, and chromogenic agents.
 11. A pharmaceutical composition comprising the antibody of claim 6 and a pharmaceutically acceptable excipient.
 12. A diagnostic composition comprising the antibody of claim
 6. 13. A method for detecting human JAK2 kinase in a sample, comprising: (a) contacting the antibody of claim 6 with the sample; and (b) detecting specific binding of the antibody to a component of the sample.
 14. A polypeptide comprising an amino acid sequence of SEQ ID NO:2.
 15. The polypeptide of claim 14, further comprising a reporter molecule.
 16. The polypeptide of claim 15, wherein the reporter molecule is selected from the group consisting of radionuclides, enzymes, fluorescent agents, chemiluinescent agents, and chromogenic agents.
 17. The polypeptide of claim 14, further comprising a signal or leader sequence.
 18. A polypeptide comprising a variant amino acid sequence of SEQ ID NO:2, wherein the polypeptide has kinase activity and the variant amino acid sequence has an insertion, deletion, or substitution of about 1 to 5 amino acids as compared to SEQ ID NO:2.
 19. A polynucleotide encoding a polypeptide comprising an amino acid sequence of SEQ ID NO:2.
 20. The polynucleotide of claim 19, comprising a nucleic acid sequence of SEQ ID NO:1. 